Next create these two tiny python scripts, and place them in your ~/bin folder.
Then either make them executable (chmod u+x FILENAME) or when setting the keybindings use python SCRIPTNAME.

file: putleft

#/usr/bin/python
import compiz
compiz.call('grid', 'put_left')

file: putright

#/usr/bin/python
import compiz
compiz.call('grid', 'put_right')

Lastly you can create two custom command shortcuts for each of these scripts in the custom commands section of the compiz config (ccsm), and hey presto - two keybinds to achieve the same effect. As mentioned above, if you made the scripts executable, the commands will be putleft and putright, else they will be python ~/bin/putleft and python ~/bin/putright.